Irix 150 mm f/2.8 MACRO 1:1 Dragonfly
7. Coma, astigmatism and bokeh
| Center, f/2.8 | Corner APS-C, f/2.8 | Corner FF, f/2.8 |
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| Center, f/4.0 | Corner APS-C, f/4.0 | Corner FF, f/4.0 |
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Astigmatism, understood as an average difference between horizontal and vertical MTF50 function values, amounted to as much as 21%. It is a high level, meaning that astigmatism is the aberration which influences the lowering of image quality near the maximum relative aperture.
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When it comes to the appearance of out-of-focus areas it would be difficult to have any reservations. The circles show even distribution of light, without any local extreme points. The rim on the edge of the frame, which intensity increases with the stopping down, doesn't seem to be especially bothersome. Still the influence of mechanical vignetting is distinct, disappearing only by f/5.6.
| Center, f/2.8 | Corner APS-C, f/2.8 | Corner FF, f/2.8 |
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| Center, f/4.0 | Corner APS-C, f/4.0 | Corner FF, f/4.0 |
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Center, f/5.6 | Corner APS-C, f/5.6 | Corner FF, f/5.6 |
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